This invention relates to an adsorptive decomposition deodorizing element which adsorbs and eliminates offensive odors and toxic gases (hereinafter referred to as xe2x80x9codor componentsxe2x80x9d) at ambient temperature, achieves high electrical energy efficiency in the step of electrical heating, requires only an extremely short rise time to attain a predetermined temperature, can quickly desorb the odor components having been adsorbed in the adsorbent so as to restore the adsorbability of the adsorbent and, at the same time, quickly oxidize and decompose the odor components having been adsorbed in the adsorbent and desorbed therefrom.
To adsorb and eliminate odor components, there have been employed adsorbents such as active carbon, zeolite, silica gel and alumina. Also, it has been a practice to catalytically decompose odor components by using oxidative decomposition catalysts. Moreover, there have been developed devices for adsorbing, decomposing and eliminating odor components by combining these techniques.
For example, JP (Kokai) Hei 4-79963 has disclosed a deodorizing device for eliminating odor components in the atmosphere with the use of an adsorbent, characterized by providing with a heating means for heating the adsorbent, a catalyst capable of making the odor components, which have been liberated from the adsorbent upon heating, odorless and harmless, and another heating means for heating the catalyst.
Further, there have been developed various heating means for desorbing the adsorbed odor components and then oxidatively decomposing the same.
For example, JP (Kokai) Hei 2-194816 has disclosed a technique for heating a deodorizing unit by using a heater which is located in the vicinity of the deodorizing unit and controlled intermittently. In the detailed description in the specification of this patent, a defroster for a refrigerator is cited as a particular example of the heater. In this case, however, the deodorizing unit cannot always achieve a satisfactory rate of temperature rise upon heating, since the heater is located in the vicinity thereof.
JP (Kokai) Hei 2-213080 has disclosed a heating device characterized by having a catalyst-coating layer on the surface thereof. In the detailed description of this patent, it is stated that examples of the heating unit useable in the heating device include coiled metal wires such as nichrome wires and kanthal wires, those in which these metal wires are enclosed in tubes made of metals, quartz or ceramics such as cordierite, mullite, alumina, zirconia, magnesia or calcia, and ceramic heaters in which electrically resistant units are enclosed in ceramics.
Further, JP (Kokai) Hei 7-246317 has disclosed an deodorizing element comprising a metallic fin providing a heater, an enamel layer formed on the surface of the fin by application and burning, and a catalyst layer formed on the enamel layer. However, such a heater or element has a large heat capacity per se and thus cannot always achieve a satisfactory heating speed. Thus, the deodorizing element has a tendency to be heated unevenly in many cases, and it is difficult to heat it uniformly.
Furthermore, JP (Kokai) Hei 7-302678 has disclosed a heating unit obtained by forming a crystallized glass layer on the surface of an electrically resistant heater and further forming a catalyst layer thereon. In the detailed description of the specification of this patent, it is stated that the crystallized glass is excellent in electrical insulating properties and adhesiveness and, therefore, it is possible to construct a small-sized heating unit. It is also stated that since the catalyst layer is located in contact with the crystallized glass layer, the catalyst layer is heated to the activation temperature of the catalyst within a short time, which makes it possible to provide a small-sized heating unit with a short rise time for eliminating and deodorizing harmful gases.
As described above, there have been developed deodorizing and cleaning techniques which comprise eliminating odor components by using adsorbents at ambient temperature, electrically heating the adsorbents either regularly or irregularly to desorb the odor components having been adsorbed therein so as to restore the adsorbability of the adsorbents and, at the same time, regenerating the catalytic activity of oxidation catalysts carried on the adsorbents by heating to the activation temperature, thus oxidatively decomposing the odor components having been adsorbed in the adsorbents and desorbed therefrom, and then repeating the above procedure to thereby eliminate the odor components for a long period of time without replacing the deodorizing unit. Also, there have been developed various means for heating deodorants consisting of adsorbents and catalysts.
Namely, a deodorant is heated so that the odor components having been adsorbed therein are efficiently desorbed and eliminated therefrom. At the same time, an oxidation catalyst carried on the adsorbent is also heated to thereby evoke its catalytic activity and thus the odor components having been adsorbed in the adsorbent and desorbed therefrom are efficiently oxidized, thus preventing the evolution of the offensive odor from the desorbed odor components. To achieve these objects, it is necessary to quickly heat up the adsorbent and the oxidation catalyst carried thereon respectively to the desorption temperature of the odor components and the reaction temperature at which the oxidation activity can be sufficiently evoked. However, the conventional heating means can frequently fail to achieve a sufficient heating speed or uniform heating. Moreover, many conventional heating means require much electrical energy and have some difficulty in processing, which restricts the patterns of the deodorizing elements. Accordingly, it has been urgently required to develop a heating means by which the above-mentioned problems can be solved, the rise time to attain a reaction temperature and the cooling period following the completion of the reaction can be shortened, uniform heating can be achieved, the evolution of any offensive odor can be prevented in the step of the regeneration thereof by heating, the heat volume of the deodorizing element can be reduced so as to save on energy consumption, and the regeneration can be performed by safe heating ever in a limited space without exerting any undesirable effect on the surroundings, thus achieving a high degree of design freedom. The present invention aims at providing an adsorptive decomposition deodorizing element which can be heated very quickly, gives little offensive odor in the step of regeneration thereof by heating, and is of light weight and exhibits excellent processability.
The present inventors have conducted extensive studies to develop an adsorptive decomposition deodorizing element which ensures an accelerated heating speed and improved uniform heating and is of light weight and exhibits excellent processability, thus being flexible and applicable for various designs. As a result, they have paid attention to mica which is of light weight, has excellent mechanical properties (electrical insulating properties , heat conductivity, mechanical strength, thermal coefficient of expansion, etc.) and a high heat resistance and can be easily processed into various complicated shapes owing to its excellent cutting and punching processability. Thus, they have developed an adsorptive decomposition deodorizing element consisting of an electrical heating unit inserted between laminated mica plates and a deodorizing unit located on the peripheral surface thereof by which odor components are adsorbed and then oxidatively decomposed by heating. The present invention has been completed based on this finding.
Accordingly, the present invention relates to an adsorptive decomposition deodorizing element comprising a heating unit having an electrical heating unit inserted between laminated mica plates and a deodorizing unit located on the peripheral surface of said heating unit.
One of the parts of the adsorptive decomposition deodorizing element of the present invention is a heating unit having an electrical heating unit inserted between laminated mica plates.